You could have said, "What do you think?" If she said something like, "Yes, I like it" or similiar or?? I would have said that's all that matters. It's not like you are lying. Kids don't need to match. Shoot - adults don't need to. If a child feels good about themselves, it shouldn't matter what they are wearing (as long as it's age appropriate). That being said, my 8 yo daughter has better fashion sense than me, my 5 yo son has been dressing himself since about 3 and w/out any input from me, always matches. So - I don't know, kids are all so unique. I work in both of my kids schools and I love love love seeing a child with their own sense of style.
I just re-read your post and a few times my daughter has either asked, "does this match" or "does it look like I'm wearing PJ'S?" (this when she is wearing yoga pants). Both times I recall saying something like, not really but you look comfy or cute or similar... because honestly, as long as she leaves the house happy and confident, again I don't really care what she wears (she's very modest so I don't have to worry about heels, short skirts, etc..)......yet! LOL!